Thin Solid Films, Vol.427, No.1-2, 324-329, 2003
Current assisted germanium-induced crystallization of amorphous silicon
Germanium-induced crystallization of amorphous silicon is reported at temperatures below 500 degreesC. Thick silicon films of 0.1 mum are covered with 500 Angstrom of germanium as the seed of crystallization. Applying an electric current enhances the growth from both cathode and anode sides. Crystallinity of the samples, treated under different annealing conditions, has been examined using XRD, SEM and TEM analyses. All these techniques verify the polycrystalline nature of the annealed films. The value of the applied voltage plays a crucial role in the crystalline quality of Si layers. While samples treated without an external voltage are not polycrystalline, an electric voltage of 10 V applied for a 1 cm separation between anode and cathode, seems suitable for achieving good polycrystalline Si layers. By increasing the applied voltage to 100 V, severe degradation is observed in both electrical and physical characteristics of the films. The size of grains varies between 0.1 and 0.2 mum, as observed using SEM.
Keywords:germanium seed;amorphous silicon;cathode;applied voltage;lateral growth;crystallization;grain size